Watch and Clock Escapements eBook

Usually the workman can manipulate the pallets to
match the escape wheel so that the teeth will have
the proper lock and drop at the right instant, and
again have the correct lock on the next succeeding
pallet. The tooth should fall but a slight distance
before the tooth next in action locks it, because
all the angular motion the escape wheel makes except
when in contact with the pallets is just so much lost
power, which should go toward giving motion to the
balance.

There seems to be a little confusion in the use of
the word “drop” in horological phrase,
as it is used to express the act of parting of the
tooth with the pallet. The idea will be seen by
inspecting Fig. 108, where we show the tooth D
and pallet C as about parting or dropping.
When we speak of “banking up to the drop”
we mean we set the banking screws so that the teeth
will just escape from each pallet. By the term
“fall” we mean the arc the tooth passes
through before the next pallet is engaged. This
action is also illustrated at Fig. 108, where the tooth
D, after dropping from the pallet C,
is arrested at the position shown by the dotted outline.
We designate this arc by the term “fall,”
and we measure this motion by its angular extent, as
shown by the dotted radial lines i f and i
g. As we have explained, this fall should
only extend through an arc of one and a half degrees,
but by close escapement matching this arc can be reduced
to one degree, or even a trifle less.

[Illustration: Fig. 108]

We shall next describe an instrument for holding the
escape wheel and pallets while adjusting them.
As shown at Fig. 107, the fork A’ is
banked a little close and the jewel pin as shown would,
in some portions, rub on C’, making a
scraping sound.

HOW TO MAKE AN ESCAPEMENT MATCHING TOOL.

[Illustration: Fig. 109]

A point has now been reached where we can use an escapement
matcher to advantage. There are several good
ones on the market, but we can make one very cheaply
and also add our own improvements. In making one,
the first thing to be provided is a movement holder.
Any of the three-jaw types of such holders will answer,
provided the jaws hold a movement plate perfectly
parallel with the bed of the holder. This will
be better understood by inspecting Fig. 109, which
is a side view of a device of this kind seen edgewise
in elevation. In this B represents the
bed plate, which supports three swing jaws, shown
at C, Figs. 109 and 110. The watch plate
is indicated by the parallel dotted lines A,
Fig. 109. The seat a of the swing jaws
C must hold the watch plate A exactly
parallel with the bed plate B. In the cheap
movement holders these seats (a) are apt to
be of irregular heights, and must be corrected for
our purpose. We will take it for granted that